1. Field of the Invention
This invention relates to a system to determine a geographical relationship between at least one diver and a surface station and to allow the surface station to emit a recall signal or for a diver to emit an emergency signal.
2. Discussion of Background
In recent years, systems have been developed for signaling the divers that a dive is over. In one such system, referred to as a "Recall System", is for the personnel operating a surface station to submerse a horn or other audible device beneath the surface of the water and send a signal for the diver(s) who have been briefed on what to listen for. The diver(s) then surface, get a fix on the surface station's location with a compass, and then re submerge and travel in the direction of the surface station. Another system, referred to as a "Drift System", which is commonly used on drift dives incorporates the use of a surface float connected to a dive leader. The surface float gives a visual reference of the dive leader to the surface station team allowing them to follow the progress of the dive and be available for recovery upon completion of the dive.
Another system, referred to as a "Night Dive System", has been developed for night diving or diving with zero visibility. This system utilizes a series of lights, both on the diver(s) and on the anchor line or set up at the surface station to aid the diver(s) in relocating the surface station at the end of the dive.
Also see U.S. Pat. No. 3,045,206, U.S. Pat. No. 3,541,717, U.S. Pat. No. 5,079,753, and U.S. Pat. No. 5,148,412 for additional teachings.
However, the above, as well as other systems, require a high level of vigilance on the part of the individual diver(s) and the surface station personnel as well as reliance on visual orientation by either or both.
With respect to the commonly used recall system, it is imperative that diver(s) first hear the signal, which may be combined or interfaced with by other underwater background noise. The diver(s) then surface to get a visual fix on the surface station utilizing a compass and dead reckoning to determine distance, and then re submerge again and travel in that fixed direction for the approximate distance. Accordingly, this system requires additional effort on the part of the diver(s) and human error is introduced into the system for returning the diver(s) directly to the surface station.
With respect to the commonly used drift diving system, the system requires that at least one diver be encumbered by controlling the surface float which gives the surface station a visual fix on the approximate location of the dive group. Accordingly, while this may be adequate for following the group, if an individual diver is separated from the group he must surface, attempt to locate the surface station, alert them by some means that he has been separated and wait for pickup. This often means that the surface station must keep visual contact of both the surfaced diver and dive group or leave the surface station's position for the required pickup and then reestablish the surface marker denoting the location of the group. Unfortunately, under severe weather conditions this type of visual reference can be hazardous if not impossible to adhere to.
With respect to the commonly used night diving or zero visibility system, the system relies on lights or marker lines to orient a diver to their location relative to the surface station. Accordingly, this often means that the diver(s) are limited to the distance that they can travel from the surface station due to length of marker line or visibility for keeping track of the lighted markers. In the case of marker lights it is further complicated if the surface station is a point of entry or exit off a shore reference which will require the diver(s) to become reoriented for termination of the dive.
However in all of the current systems available it is not typical for the diver(s) to signal the surface station of an emergency situation (i.e., out of air, entangled at depth, in danger of decompression sickness, swept off location by current, etc.). Accordingly, a diver must signal to his dive buddy and/or surface, signal the surface station of distress and hope that the surface station personnel will notice and locate him and then act accordingly. Unfortunately, at present, the common doctrine is to stay on station with the group until recovered and then aid the distressed diver(s).